Insight into the electrochemical behavior of lithium-sulfur cells assisted by potassium hydroxide activated carbon black and polyaniline nanorods

Potassium hydroxide (KOH) activated Super P (Ksp) was adopted to prepare Ksp/S composite by chitosan assisted chemical synthesis approach. The Ksp/S was further heat treated at 159 °C and then coated by polyaniline (PANI) to fabricate Ksp/S-159 and Ksp/S-159/PANI composites, respectively. The heat treated binary sulfur/carbon and PANI coated ternary sulfur complex showed enhanced cycle performance and rate capability. However, the electrochemical behavior of Ksp/S-159 and Ksp/S-159/PANI can be greatly affected by the discharge current. The Ksp/S-159/PANI composite delivers an initial discharge capacity of 1202.3 mAh g^-1 and keeps 954 mAh g^-1 after 100cycles at 0.5 mA cm^-2 (0.31C). The Ksp/S-159 presented a maximum capacity up to 892.5 mA h g^-1 at 2 ma cm^-2 (1.26C) and retained about 409.2 mA h g^-1 after 500 cycles. The PANI coated ternary sulfur complex shows good electrochemical performance at low discharge current while the heat treated sulfur/carbon shows good rate capability at high discharge current. The different electrochemical behavior is fully discussed to illustrate the complex Li-S discharging process.